1. Field of the Invention
The invention relates to a hybrid vehicle driving apparatus.
2. Description of Related Art
There is known a hybrid vehicle driving apparatus which includes a rotor shaft of a first electric motor that is disposed on a first axis, a power distribution mechanism that includes a planetary gear device is disposed on the first axis, and an output gear shaft that serves as an output member of the power distribution mechanism on the first axis. The hybrid vehicle driving apparatus also includes a counter shaft that is disposed on a second axis, a rotor shaft of a second electric motor that is disposed on a third axis, a power transmission shaft that is disposed on the third axis, and a differential gear that is disposed on a fourth axis. In addition to the above, the hybrid vehicle driving apparatus includes a casing that is made up of a plurality of case members. The casing supports the rotor shaft of the first electric motor, the power distribution mechanism, the output gear shaft, the counter shaft, the rotor shaft of the second electric motor, the power transmission shaft and the differential gear.
Japanese Patent Application Publication No. 2001-187535 (JP 2001-187535 A) discloses a hybrid vehicle driving apparatus as described above. In JP 2001-187535 A, a hybrid vehicle driving apparatus includes a rotor shaft (first rotor shaft) of first electric rotation means (first electric motor), a planetary gear (power distribution mechanism), a vehicle-travel rotating shaft (output gear shaft), a counter shaft, an output shaft (second rotor shaft) of a second electric rotation means (second electric motor), a counter drive gear (power transmission shaft), a differential device (differential gear) and an integrated case (casing). The rotor shaft, the planetary gear and the vehicle-travel rotating shaft are disposed on a first axis. The vehicle-travel rotating shaft is linked to the planetary gear. An end portion of the vehicle-travel rotating shaft is provided with a counter drive gear. The counter shaft is disposed on a second axis. The counter shaft is provided with a large gear and a small gear. The output shaft and the counter drive gear are disposed on a third axis. The differential device is disposed on a fourth axis. The integrated case is made up of a housing, a case and a rear cover. The rotor shaft, the planetary gear, the vehicle-travel rotating shaft, the counter shaft, the output shaft, the counter drive gear and the differential device are rotatably supported by the integrated case.
In the hybrid vehicle driving apparatus of JP 2001-187535 A, the vehicle-travel rotating shaft, the counter shaft, the output shaft, the counter drive gear and the differential device are rotatably supported by the case. The rotor shaft is rotatably supported by a center support. that the center support is fixed to the case by bolts or the like. If the rotor shaft is supported by the center support, the accuracy of supporting the first electric means declines due to the mounting error of the center support. In addition, since the number of component parts increases, the weight of the vehicle or cost may increase.